Ceramic thermal spray coatings are used in various applications according to the properties of the constituent ceramics. For example, aluminum oxide thermal spray coatings are used as protective coatings for various members because aluminum oxide exhibits high electric insulation, abrasion resistance, and corrosion resistance. Yttrium oxide thermal spray coatings are used as protective coatings for members in semiconductor device production apparatuses because yttrium oxide exhibits high plasma erosion resistance (see, for example, patent document 1 and patent document 2).
A ceramic thermal spray coating can be formed by thermally spraying a slurry containing ceramic particles (see, for example, patent document 3). However, there is a problem such that the thermal spraying of slurries is lower in thermal spraying efficiency as compared with the thermal spraying of powders. In order to improve the thermal spraying efficiency of the thermal spraying of a slurry, it is effective to increase the amount of the ceramic particles contained in the slurry. However, in such a case, the fluidity of the slurry is degraded, and consequently, it is sometimes difficult to form a thermal spray coating.